Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Options (in shares):
Outstanding beginning of the period (in shares)	6,089,938
Granted (in shares)	1,718,332
Forfeited (in shares)	131,846
Exercised (in shares)	707,291
Outstanding end of the period (in shares)	6,969,133	6,089,938
Exercisable at end of the period (in shares)	3,471,017
Weighted-Average Exercise Price (in dollars per share):
Outstanding beginning of the period, weighted average exercise price (in dollars per share)	$ 9.63
Granted, weighted-average exercise price (in dollars per share)	14.36
Forfeited, weighted average exercise price (in dollars per share)	13.75
Exercised, weighted average exercise price (in dollars per share)	3.17
Outstanding end of the period, weighted average exercise price (in dollars per share)	11.37	$ 9.63
Exercisable at the end of the period, weighted average exercise price (in dollars per share)	$ 7.96
Outstanding, weighted-average remaining contractual term (years)	7 years 8 months 12 days	7 years 9 months 18 days
Exercisable, weighted-average remaining contractual term (years)	6 years 6 months
Outstanding, aggregate intrinsic value	$ 43,287	$ 30,066
Exercisable, aggregate intrinsic value	33,348
Options Additional Information:
Options exercised intrinsic value	$ 8,400	$ 1,700	$ 638
Options grants in period, weighted average grant date fair value (in dollars per share)	$ 6.53	$ 7.85	$ 6.24
Options vested in period fair value	$ 8,700	$ 5,100	$ 2,300
Share-based compensation expense	11,000	7,385	3,370
Employee and Nonemployee Stock Options
Options Additional Information:
Options unrecognized compensation expense	$ 20,600
Options unrecognized compensation expense, period for recognition	2 years 9 months 26 days
Share-based compensation expense	$ 7,600	7,300	3,100
Nonemployee Stock Options
Options Additional Information:
Share-based compensation expense	$ 236	$ 1,800	$ 1,600